\begin{table}%t3
%\centering
\par
\caption{\label{tab:densities}Derived column densities for HOCN and HCNO, and abundance ratios.}
\par
%\centering
\par
\begin{tabular}{lcccccccc}
\hline 
\hline\noalign{\smallskip}
Source    & $N$ (HOCN)   & HOCN/H$_2$\tablefootmark{a}          & $N$ (HCNO)    & HCNO/H$_2$\tablefootmark{a}       & $n$(H$_2$)        & HNCO/HOCN  & HNCO/HCNO  &  HCNO/HOCN \\
          & $10^{10}$~cm$^{-2}$ & $\times10^{13}$ & $10^{10}$~cm$^{-2}$ &$\times 10^{13}$ &   10$^5$~cm$^{-3}$  &            &            & \\
\hline\noalign{\smallskip}
B1-b      & 14.3(6)/10(1) & 11/7.7       & 21(1)/17(4)\tablefootmark{b} & 16/13     & 20(5)             &  62/80     & 42/47      & 1.5/1.7 \\
L1527     &  3.8(5)/2.7(2) &  13/9.0     &  6(1)/4(1)\tablefootmark{b}  & 21/15     & 5(1)\tablefootmark{b}          &  58/67     & 34/40      & 1.7/1.7 \\
L1527-B   &$\leq$1/1.5    & $\leq$3.3/5.0      &  5(1)/4(1)\tablefootmark{b}  & 17/13      & 5(1)\tablefootmark{b}          &$\geq$90/53    & 18/20      &$\geq$5/2.7 \\
L1544     &  9(1)/8.6(2)  & 6.9/6.6      &  6(3)/6(2)\tablefootmark{b} & 4.6/4.8       & 0.7(2)\tablefootmark{b}        &  59/48     & 88/65      & 0.7/0.7 \\
L183      &  7(3)/4.0(2)  & 88/53      &  6(2)/5(1)\tablefootmark{b}  & 75/66      & 5(1)              &  51/63     & 60/50      & 0.8/1.2 \\
TMC-1     &$\leq$0.9/1.9  & $\leq$9/19       &$\leq$1.3/1.4\tablefootmark{b} & $\leq$13/14     & 0.3(1)\tablefootmark{b}  \\
IRAS 16293-2422 & 125(4)/160(1) & 3.6/ 4.6 &$\leq$115/60   & $\leq$3.3/1.7      & 2.5(5)            & 27/21      &$\geq$30/57    &$\leq$0.9/0.4 \\
\par
SgrB2M-B  &  2600\tablefootmark{c}  & $\approx$260    &$\leq$17         &  $\leq$1.7&     $\approx$1.4\tablefootmark{a}           & 181        &$\geq$30000    &$\leq$0.006 \\
SgrB2M h.c.   &  70000\tablefootmark{c} & $\approx$260  &$\leq$5818       & $\leq$22 &     $\approx$750\tablefootmark{a}         &  90        &$\geq$1031      &$\leq$0.083 \\
SgrB2M  ext.  &  750\tablefootmark{c} & $\approx$75  &$\leq$14       & $\leq$1.4 &     $\approx$1.4\tablefootmark{a}         &  230        &$\geq$12143      & $\leq$0.019 \\
SgrB2N  h.c.  &  670000\tablefootmark{c} &$\approx$5200 &$\leq$79139      &  $\leq$609   &  $\approx$540\tablefootmark{a}              &  313        &$\geq$2654     &$\leq$0.118 \\
SgrB2N  ext.  &  1600\tablefootmark{c} &$\approx$160 &$\leq$45      &  $\leq$4.5   &  $\approx$1.4\tablefootmark{a}              &  181        &$\geq$6444     &$\leq$0.028 \\
SgrB2S    & 4200\tablefootmark{c}   & $\approx$420   &$\leq$40         &   $\leq$4.0  &  $\approx$1.4\tablefootmark{a}             &  43        &$>$4500     &$<$0.010 \\
\hline
\end{tabular}
\tablefoot{L1527-B corresponds to the position $(20'',~-20'')$ of this source, and SgrB2M-B to the offset 
$(20'',~100'')$ with respect to SgrB2M, h.c. refers to a hot core component, and ext. to the extended gas around this hot core. 
The first entry in the $N$(HOCN), $N$(HCNO) values, and in the abundances 
ratios corresponds to the column density obtained from the rotational diagrams, while the second one corresponds 
to the same parameter obtained from the $LVG$ calculations. Column densities in cold cores for HNCO are from 
\citet{Mar09}, and those for the GC clouds from \citet{Bru09b}.
For IRAS 16293-2422 we have assumed $N({\rm HNCO})=3.4\times10^{13}$ \citep{Dis95}. 
$^a$ Assumed H$_2$ column densities are: 
B1-b: $1.3\times10^{23}$~cm$^{-2}$ \citep{Hir99};
L1527: $3\times10^{22}$~cm$^{-2}$ \citep{Jor02};
L1544: $1.3\times10^{23}$~cm$^{-2}$ \citep{War99};
L183: $7.6\times10^{21}$~cm$^{-2}$ \citep{Swa89};
TMC-1(CP): $1\times10^{22}$~cm$^{-2}$ \citep{Cer87};
IRAS 16293-2422: $3.5\times10^{24}$~cm$^{-2}$ \citep{Bot04};
SgrB2M-B, SgrB2S, SgrB2M ext., and SgrB2N ext.: $1\times10^{24}$~cm$^{-2}$ \citep{Lis1990}; 
SgrB2M h.c.: $2.7\times10^{25}$~cm$^{-2}$ \citep{Liu1999}; and 
SgrB2N h.c.: $1.3\times10^{25}$~cm$^{-2}$ \citep{Belloche2008}.
Source sizes for the GC clouds from \cite{Bru09b}, assumed distance to the GC clouds 8 kpc \citep{Reid1993}. \tablefootmark{b} From \citet{Mar09}.
 \tablefootmark{c} From \citet{Bru09b}.}\vspace*{2mm}
\end{table}